Polymer Interphase Materials by Forced Assembly

Abstract

The interphase between two immiscible glassy polymers was probed using nanolayer films with tens to thousands of alternating layers of two polymers. Various combinations of poly(methyl methacrylate), polycarbonate, and a series of styrene-acrylonitrile copolymers were brought together by forced assembly. Continuous nanolayers with thickness on the size scale of the interphase were observed directly using atomic force microscopy. Interphase thickness was extracted from the layer thickness dependence of oxygen permeability. The interphase thickness showed the predicted dependence on the interaction parameter and correlated with interphase strength as measured with the T-peel test. Interphase specific volume, as determined by density, exhibited both positive and negative deviations from constituent additivity. The deviations correlated with the change in free volume hole size from positron annihilation lifetime spectroscopy but did not correlate directly with the parameter. The origin of the deviations was found in the nature of chain packing in the interphase, as evidenced by nonadditivity in entanglement molecular weight. The volumetric effects accounted for the glass transition behavior of the interphase material.

Study of the multilayered nanostructure and thermal stability of PMMA/PS amorphous films

“…Polystyrene (PS) was provided by The Dow Chemical Company (Styron 685D). The molecular weight, determined by GPC, was 132 and 527 kg mol À1 and the density, measured with a density gradient column, was 1.1923 and 1.0450 g cm À3 respectively [11]. Films were prepared using the layer-multiplying process as described elsewhere [30].…”

“…Even for two chemically different polymers, their interfaces are not completely sharp and, in spite of the highly unfavourable enthalpic interaction between them, a small extent of interpenetration of molecules is allowed. In this way, a new "interphase" is created whose thickness, in case of poly(methyl methacrylate)/polystyrene (PMMA/PS), has been probed to be around 5e6 nm [10,11]. As polymer layers become thinner and comparable to the size of the interphases, the bulk material may behave as an entirely new interphase material [9,11,12].…”

“…In this way, a new "interphase" is created whose thickness, in case of poly(methyl methacrylate)/polystyrene (PMMA/PS), has been probed to be around 5e6 nm [10,11]. As polymer layers become thinner and comparable to the size of the interphases, the bulk material may behave as an entirely new interphase material [9,11,12]. For such systems, it is important to understand the extent to which the nanoscale size of the layers as well as the interfaces affect the properties of both the overall material and the individual layers.…”

“…Information on the average layer thicknesses over the entire film crosssection obtained by USAXS will be compared with local average layer thicknesses as derived from selected AFM images [11]. It is worth pointing out that this is the first time that a regular structure, with well-defined large spacings up to 500 nm, of two immiscible glassy polymers (PMMA/PS) has been investigated by means of USAXS.…”

Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites

“…Multilayer coextrusion is an attractive technique to produce up to thousands of alternating layers in films with individual layer thicknesses from 10 nm to multiple mm [17,18]. In pioneering work, Baer and coworkers have used this "forced assembly" technique and have shown that immiscible polymer pairs and filled/unfilled polymers can be forced to combine into a unique multilayer structure, accompanied with interesting confined crystallization effects [19], gas barrier properties [20], and optical properties [21].…”